1. Field of the Invention
The present invention relates to an object detection method and apparatus, and more particularly, to an object detection method and apparatus that separates and detects an object from a current image frame.
2. Description of the Related Art
Main functions of an image processing system that captures an image of an object and processes image data are to identify a background or object in the captured image and to discriminate between objects. Thus, the image processing system can identify background and object images and perform relevant functions.
Image processing to detect an object in an image is performed such that pixels constituting an object are searched for in an image plane using an image scanning algorithm and the found pixels are binarized and are then labeled and grouped. When the pixels have been grouped into an object, the image processing is completed. Image processing performance such as robustness or processing speed varies depending on an algorithm and a programming technique employed for each process.
In a line scanning method, pixels are searched for in the entire region of an image. Although this method has an advantage in that image data of the entire region of an image plane is searched, it has a problem in that it takes a long time to search the entire image region.
If the position of an object can be predicted, it will be possible to significantly reduce the time required for the search by searching for pixels only in a region corresponding to the predicted position. One example is a window tracking method in which the position of an object is predicted and pixels are searched for only in a specific region (window) in which it is predicted that the object will be located every frame. This method has higher processing speed than the line scanning method. However, the window tracking method also has the following problems. If the size of the window is reduced, the object may exit the window region, leading to a failure to detect the object, although the time required for image processing is reduced. On the other hand, if the size of the window is increased, the time required for image processing is increased although the possibility that the object will exit the window region is reduced.
As described above, the line scanning method has a problem that it requires a long search time since the entire region of the image plane should be searched although it has an advantage in that all pixels of the object to be detected can be found. On the other hand, the window tracking method has a problem in that the accuracy of prediction of the position of an object should be higher than a specific level in addition to the problem that the size of the window should be adjusted appropriately.
A dot-line scanning method may be employed to achieve the advantages of the two methods while overcoming their problems. The dot-line scanning method searches for pixels of an object while jumping pixels at specific pixel intervals in the image plane. This method has an advantage in that the image processing time is significantly reduced compared to the line scanning method.
However, the conventional dot-line scanning method has the following problems. Although an approximate pixel region constituting an object can be found since the pixel region constituting the object is searched for in the image while jumping pixels at specific pixel intervals, the accurate appearance of the object cannot be detected since an entire pixel region of the object cannot be found.
The conventional dot-line scanning method performs labeling and grouping, which are general image processing methods, in such a manner that all pixels of an image are labeled and are then grouped based on the labeled data. That is, scanning is performed twice since the pixel region of the object is scanned once and the labeled data is then scanned once more. This increases required memory capacity and calculation complexity and also increases the image processing time.